PHP自动生成月历代码

<?php
/* 
function written by nelson neoh @3/2004. 
for those who wants to utilize this code, please do not remove this remark. 
if you have done any enhancement to this code, please post the copy at http://www.dev-club.com php board.  thank you.

function usage: calendar(month,year)
*/

function calendar($mm,$yyyy){
    if($mm=="") $mm = date("m");
    if($yyyy=="") $yyyy = date("y");
    if(checkdate($mm,1,$yyyy)){
        $stringdate = strftime("%d %b %y",mktime (0,0,0,$mm,1,$yyyy));
        $days = strftime("%d",mktime (0,0,0,$mm+1,0,$yyyy));
        $firstday = strftime("%w",mktime (0,0,0,$mm,1,$yyyy));
        $lastday = strftime("%w",mktime (0,0,0,$mm,$days,$yyyy));
        $printdays = $days;
        $premonth = strftime("%m",mktime (0,0,0,$mm-1,1,$yyyy));
        $preyear = strftime("%y",mktime (0,0,0,$mm-1,1,$yyyy));
        $nextmonth = strftime("%m",mktime (0,0,0,$mm+1,1,$yyyy));
        $nextyear = strftime("%y",mktime (0,0,0,$mm+1,1,$yyyy));
        print("<table border=\"1\" cellpadding=\"1\" cellspacing=\"1\">");
        print("<tr><th valign=\"top\"><a href=\"".$_server['php_self']."?nb=".$_get["nb"]."&mm=".$premonth."&yy=".$preyear."\">p</a></th>");
        print("<th colspan=\"5\" valign=\"top\">".strftime("%b %y",mktime (0,0,0,$mm,1,$yyyy))."</th>");
        print("<th valign=\"top\"><a href=\"".$_server['php_self']."?nb=".$_get["nb"]."&mm=".$nextmonth."&yy=".$nextyear."\">n</a></th></tr>");
        print("<tr style=\"font-family: verdana; font-size:x-small\">");
        print("<th>sun</th><th>mon</th><th>tue</th><th>wed</th><th>thu</th><th>fri</th><th>sat</th></tr>");

        $currentdays = 1;
        for($a=1;$a<=5;$a++){
            print("<tr align=\"left\" valign=\"top\" style=\"font-family: verdana; font-size:x-small\">");
            $diffdays = $firstday-$lastday;
            if($firstday>$lastday && $currentdays ==1 && ($diffdays<>1)){
                for($x=$lastday;$x>=0;$x--){
                    $printdays = $days-$x;
                    print("<td>$printdays</td>");
                }
                for($z=1;$z<$firstday-$lastday;$z++){
                    print("<td> </td>");
                }
                for($y=$firstday;$y<7;$y++){
                    print("<td>$currentdays</td>");
                    $currentdays++;
                }
            } elseif($firstday!=0 && $currentdays==1){
                for($z=1;$z<=$firstday;$z++){
                    print("<td> </td>");
                }
                for($y=$firstday;$y<7;$y++){
                    print("<td>$currentdays</td>");
                    $currentdays++;
                }
            } else {
                for($u=1;$u<=7 && $currentdays<=$days;$u++){
                    print("<td>$currentdays</td>");
                    $currentdays++;
                }
            }
            print("</tr>");
        }
        print("</table>");
    }
}
?>